Some users of devices residing on a network find it desirable to locate all or a class of other devices on the network. For example, a user may wish to have a list of all the printers of a certain brand, along with information about those printers that are on the same sub-network. Many networked printers are delivered with software which allows users to install the printer's driver onto a user's host device. This installer software allows users to search for printers on their network. However, if the printer was attached to a different IP subnet than the user's host device, the installer could not locate the printer(s) without additional input from the user. Since many of users are not technically knowledgeable about their company's network topology, they could not answer the questions prompted them by the installer and could not find the printer to be installed.
There are many problems with existing tools for locating devices on networks. First, traditional management tools generally only find devices of a particular manufacture or type. For example, CISCO tools only find CISCO devices; 3COM tools only find 3COM devices.
Second, using existing protocols, such as Simple Network Management Protocol (SNMP) typically means searching for other devices on the network by sending (User Datagram Protocol) UDP messages to the sub-network and then waiting for particular responses from network devices that are listening on the same sub-network. UDP is a protocol that offers a limited amount of service when messages are exchanged between network devices in a network that uses the Internet Protocol (IP). A persistent problem with UDP alone is the loss of information packets due to congestion in the network or the receiving device.
A third problem also exists when attempting to locate or find devices with no IP address. Service Location Protocol (SLP), described in the Internet Request For Comments document 2165 (RFC 2165), has been used as a substitute or to supplement UDP-based SNMP broadcast and responses. SLP provides a means to send a list of devices that have already responded in the broadcast request such that those who have already responded will not do so again. However, using SLP may result in slower and more cumbersome location of devices on the network because of it's complexity and lack of specialization.
Another problem with traditional network management tools using IP multicasting is that they talk to routers which require registration with the router. Furthermore, registration with routers is considered to be a security risk for some applications by many.
The 935 application overcomes many of these problems. The 935 application describes a system and method for network device location that provides a faster and more exhaustive search, and uniquely identifies those devices on the same subnet without relying on their IP address. A system for network device location, according to the 935 application, includes a first device for sending an HTTP request to a device having a known location on the network for a list of addresses of devices on the network; and a second device having a known location on the network, responsive to the HTTP request, for sending a DLP (device location protocol) request to devices on the network, responsive to DLP responses from devices on the network, for generating a list of network addresses of responding devices on the network, and for sending the list of network addresses of devices on the network to the first device; wherein the DLP request includes a list of network addresses of devices that have previously responded such that only those devices not on the list will respond; and wherein the length of each network address is included before each network address in the list. The 935 application also describes a system and method which assigns an IP address to devices on the network.
It would be desirable to improve the device search capabilities of a network management tool so it can find devices on remote subnets without user intervention. It would be desirable to improve the search capabilities of a printer driver installer so that, in many cases the installer can find printers on remote subnets without user intervention. It would also be desirable to improve the device search capabilities of a network management tool so that the tool can find devices, such as printers that have not been assigned an IP (Internet Protocol) address.